This invention relates to improvements in an elevator terminal deceleration system for decelerating and landing an elevator car at a terminal floor.
Speed feedback control systems for controlling the speed of the elevator car in accordance with a command deceleration signal are employed in order that the elevator car is decelerated with a comfortable ride maintained and lands accurately at that floor of a building on which the car is predetermined to be stopped due to a call registered thereon or registered on the elevator car. It has been recently proposed that an electronic computer be used to cause the elevator car to decelerate and land at such a predetermined floor.
To this end, there have been various types of elevator terminal deceleration systems already proposed. One type of the proposed elevator terminal deceleration systems has comprised counter means for counting pulses corresponding to a distance of movement of an elevator car, and an electronic computer for receiving a count from the counter means upon the elevator car reaching a predetermined distance short of a terminal floor to subtract the count from the predetermined distance preliminarily stored therein so as to calculate a residual distance to the terminal floor and to generate a command normal deceleration signal having a magnitude successively decreased in accordance with the calculated residual distance.
On the other hand, when the elevator car approaches the terminal floor to successively engage a plurality of terminal sensors disposed adjacent to the terminal floor within an associated hoistway, a command terminal deceleration generator means generates a command terminal deceleration signal having a magnitude successively decreased in accordance with the actual position of the elevator car and always higher than that of the command normal deceleration signal. Then, a comparison circuit means compares the command normal deceleration signal with the command terminal deceleration signal to deliver the smaller of the two signals. The elevator car safely decelerates and lands at the terminal floor in accordance with the smaller signal or the command normal deceleration signal.
If the command normal deceleration signal is equal to or greater than the command terminal deceleration signal for some reason, for example, an error in a positional signal indicating the actual position of the elevator car, then the former signal similarly controls the elevator car to decelerate and land at the terminal floor.
However, the number of terminal sensors has been limited so as to make it difficult to smoothly change the resulting command terminal deceleration signal, resulting in an uncomfortable ride. In order to prevent any malfunction, the command terminal deceleration signal may also be distant from the command normal deceleration signal. However, this has caused an increase in delay relative to the command normal deceleration signal, resulting in the deterioration of the landing accuracy.
Accordingly, it is an object of the present invention to provide a new and improved elevator terminal deceleration system by which an elevator car can decelerate and land at a terminal floor with a high landing accuracy while a comfortable ride is maintained even upon the occurrence of a fault on either a positional signal indicating the actual position of the elevator car and a call sensing signal indicating which of floors has a call registered thereon or registered on the elevator car.